This revised R21 research grant application represents a partnership between the YMCA of Greater New York (YNY) and Columbia University. Over 2 years, the planned study will adapt a parent-involvement program for combined use with a previously tested program for girls called RealTeen. The resulting combined programs will be tested with a sample of adolescent girls enrolled in YNY after-school programs and the mothers of these girls. Besides testing the outcomes of both prevention programs, the planned research will examine intervention effects on mediator variables of girls'coping responses, refusal skills, mood management skills, conflict resolution abilities, problem-solving skills, self-efficacy to avoid substance use, body esteem, normative beliefs about drug abuse, social supports, disciplinary and delinquency behaviors, and conduct problems. Additional study measures will examine the extent to which the intervention programs affected girls'mothers'use of family rituals, rules against substance use, and mother-daughter affect. Other study aims are to relate girls'and mothers'measured mediator variables to girls'drug use, to test dose-response intervention effects, and to determine whether intervention exerted differential effects related to girls'ethnic-racial group profiles. Girls and their mothers will complete all study measurements online at pretest, posttest, and 6-month follow- up. Intervention delivery will occur via the Internet and CD-ROM. YNY staff and administrators are full participants in all aspects of the planned research, including the analysis and interpretation of data, the dissemination of findings, and requests for follow-on support. Through the R01 research grant mechanism, that follow-on support will sponsor a large- scale test of parent-involvement and RealTeen prevention programs with girls enrolled in YNY after- school programs and the mothers of these girls. In the follow-on test, not only will we measure end- point substance use outcomes, but also we will examine program implementation variables of fidelity and participant feedback and parameters relevant to the adoption and maintenance of the prevention programs within the YNY community. YNY administrators are committed to marketing the tested programs through the 22 YNY centers in New York City and nationwide. PUBLIC HEALTH RELEVANCE: In response to growing rates of substance use among American adolescent girls, this revised and resubmitted grant application describes a collaborative study to refine and pilot test gender- specific and parent-involvement approaches to drug abuse prevention. Study participants will be adolescent girls and their mothers recruited from YMCA centers of Greater New York (YNY). After completing pretest measures via the Internet, girls and their mothers will be divided into intervention and control arms. Girls and mothers in the intervention arm will interact online with prevention programming, and all participants will complete posttests and follow-up measurements online. Once the prevention approaches are carefully tested in a large-scale clinical trial, they will be disseminated nationally through YMCA centers.